With any luck this re work may keep the crack closed up.
Fix cracked window sill.
It is possible to fill in quite sizeable holes with the masonry filler method but if the edges are crumbling away you ll need to build moulds to shape the sill correctly a job that s probably beyond most diyers skill level.
Caulk tube versions are easiest to use just squeeze the sealer into the crack then smooth it with a plastic spatula or putty knife and peel off the tape.
Spread and flatten the caulk with a small putty knife.
Repairing window sill damage is typically simple.
Then we used a hammer and banged popped the sill upwards being careful to avoid any further damage.
You will need to raise one side or the other with plastic.
See below for tools and a shoppin.
Switch to a 220 grit sanding sponge to finish off with a very smooth surface.
We pulled out the rest of the nails that were left behind.
Fit the narrow tip of a bottle of silicone latex caulk into each crack and overfill it by about inch.
In a disposable container mix up your batch of liquidwood remember the 1 to 1 proportions and let it setup for about 15 minutes.
Chip says apply painter s tape around the edges of each crack.
Scrape away any mess with the edge of the knife.
Sand the surface with a 100 grit sanding sponge.
Other sill repairs can extend from basic maintenance to reconstruction of the sill.
The sill or lower horizontal wood plate extends into the room creating a target for impacts and other damaging factors.
First we ran a cutting blade this is my favorite caulk removing tool around all the edges including between the underneath trim and the window sill.
Check for sill movement such as a crack where one side has settled or is down farther than the other side causing a crown and a crack.
A split cracked or simply weathered window sill can detract from an otherwise beautiful window.
If there is not one there you may want to push up the cracked sill and install a skirting board to help support the sill.
I prefer using a glue brush to help the epoxy work down into cracks and crevices.
Repairing weathered sill finishes is simply a matter of sanding and repainting.
Step 1 fix any small or medium cracks in your concrete window sill with caulk.
Sometimes a skirting trim or board is installed under a sill like this to help support the sill.
Once it is ready you can apply it to the surfaces that require stabilization and repair.
Fill thin fissures 1 8 inch to 1 4 inch wide with a concrete patch sealer.